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Semantic memory

Friday, September 30th,   2011 [17:20 - 19:20]

PS_1.082 - Function and manipulation tool knowledge coded in lateral anterior temporal lobe and inferior parietal lobule: Evidence from an rTMS study

Ishibashi, R. 1, 2 , Lambon Ralph, M. 2 , Saito, S. 1 & Pobric, G. 2

1 Department of Cognitive Psychology in Education, Kyoto University, Japan
2 Neuroscience and Aphasia Research Unit, University of Manchester, UK

A remarkable cognitive ability in humans is the competency to use a wide variety of different tools. Two cortical regions, the anterior temporal lobes (ATL) and left inferior parietal lobule (IPL), have been proposed to make differential contributions to two kinds of knowledge about tools: function vs. manipulation. We used repetitive transcranial magnetic stimulation (rTMS) and two semantic decision tasks to assess the role of these regions in healthy participants. Participants made semantic decisions about the function (what for) or manipulation (how) of tools used in daily life. The stimulation of ATL resulted in longer responses for the “function” judgments, whilst stimulation of IPL yielded longer responses for the “manipulation” judgments. In line with the neuropsychological literature, these results indicate ATL and IPL disproportionately contribute different aspects of the representation of tools, supporting the “hub-and-spoke” theory of semantic memory.

PS_1.083 - Individual differences in strength of category-based relations vs. event-based relations

Mirman, D. & Graziano, K. M.

Moss Rehabilitation Research Institute, Philadelphia, USA

Knowledge about word and object meanings can be organized around categories, such as fruits or mammals, which are defined by shared features, or around events such as eating breakfast or taking a dog for a walk. An eye-tracking study showed that both kinds of knowledge are automatically activated during comprehension of a single spoken word, even when the listener is not required to perform any active task. The results further revealed that an individual’s relative activation of category-based relations compared to event-based relations predicts that individual’s tendency to favor category or event relations when asked to choose between them in a similarity judgment task. These results argue that individuals differ in the relative strengths of their category-based and event-based semantic knowledge and suggest that meaning information is organized in two parallel, complementary semantic systems.

PS_1.084 - Possible cerebellar contributions to semantic fluency

Kent, J. 1 , Matthews, S. 1 , Bolbecker, A. 1, 2 , Rass, O. 1 , Klaunig, M. 2 , Jones, M. 1 , O'Donnell, B. 1, 2, 3 & Hetrick, W. 1, 2, 3

1 Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, USA
2 Larue D. Carter Memorial Hospital, Indianapolis, IN, USA
3 Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN, USA

Although the role of the cerebellum in motor coordination has long been appreciated, only recently has its role in cognitive processes been explored. Theoretical models of psychopathology identify the cerebellum as a critical node in a coordinative network regulating cognition. We tested the hypothesis that performance on a cerebellar-dependent associative learning task (delay eyeblink conditioning) would be correlated with semantic fluency performance in healthy individuals (n=10) but not in schizophrenic (n=8) and bipolar (n=11) participants, where cerebellar anomalies have been reported. Subjects completed delay eyeblink conditioning (EBC) and a semantic fluency task. During EBC, an airpuff that elicits an unconditioned blink response is repeatedly paired with a tone. Subjects develop a conditioned blink response (CR) to the tone that precedes the airpuff. In the semantic fluency task, subjects name exemplars from the “animal” category for two minutes. In healthy participants, but not in schizophrenia or bipolar participants, the number of items generated on the semantic fluency task correlated with CR timing (r(9)=-0.71, p=0.02). This relationship between performances on a cerebellar-mediated task (delay EBC) and semantic fluency in healthy participants supports the hypothesis that the cerebellum is involved in the coordination of cognitive processes in individuals with intact cerebella.

PS_1.085 - Playing patty-cake interferes with comprehending the names of objects that are interacted with manually

Yee, E. 1, 2 , Chrysikou, E. 2 , Hoffman, E. 2 & Thompson-Schill, S. 2

1 Basque Center on Cognition Brain & Language
2 University of Pennsylvania

How do we know the meaning of words? Sensorimotor-based theories of semantic memory claim that semantic 
information about an object is distributed over the neural substrates that are
 invoked when we perceive and interact with it. Hence,
 occupying a neural substrate that is an important part of an object’s
 representation (e.g., with a concurrent secondary task) should interfere with
 accessing that representation. In the current work, participants made concreteness judgments about (heard) names of objects while either simultaneously performing a patty-cake -like task on a table, mentally rotating objects, or performing no concurrent task. Objects varied in the extent to which one interacts with them manually
 (e.g., tiger=low manual interaction, pencil=high manual interaction). We found that performing a concurrent task increased
 errors for all objects. Critically, however, during the patty-cake task, errors were
 greatest for objects rated as high in manual interaction. (In contrast, the concurrent mental rotation task did not disproportionately increase errors for manual objects.) These findings suggest that engaging brain regions underlying manual interaction (with an incompatible manual task) interferes with comprehending the names of that are manually experienced. Hence, these regions appear to be part of (rather than peripheral to) the representation of frequently manipulated objects.

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